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Insulate A Fireplace

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by jeffs, Nov 21, 2005.

  1. jeffs

    jeffs Member

    Joined:
    Nov 21, 2005
    Messages:
    49
    Loc:
    Central-PA
    We have a pre-fab fireplace (Heatilator) with glass doors. The fireplace extends into our family room with stone-faced walls built around it at the sides, and a raised stone hearth in front. In winter, ice cold air pours out the bottom of the fireplace, and the hearth is also cold as ice. I created an insulated cover for the front of the fireplace, which does a decent job of blocking the draft, but is a pain to take in and out when we want to use the fireplace.

    The fans in the unit are extremely noisy, so we never use them. Is there any kind of insulation I can stuff in the air space below the firebox to stop the drafts? Or will it just come out the top then?

    We had a similar fireplace at a previous house, and it didn't have cold-air drafts anywhere near what we have with this one.

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  2. webbie

    webbie Seasoned Moderator Staff Member

    Joined:
    Nov 17, 2005
    Messages:
    12,379
    Loc:
    Western Mass.
    DON'T DO IT!

    Ok, I will stop shouting, but here's the deal. Closing off any air vents in pre-fab fireplaces can cause immediate house fires! Those are the vents that cool the fireplace when it is burning.

    If the problem is when you are not using it, you can use something like that magnetic vinyl to cover the vents WHEN THE FIREPLACE IS OFF only!

    This is a major problem with air cooled double wall fireboxes. Basically, you have this giant metal box with nothing between it and the outside air (that can come up or down the chimney when not in use)...

    It's another one of those strange things - this should not be allowed with current building codes. The makers should have to deliver a system that does not cause great heat loss to the home when not in use (which is most of the time!)...
  3. TBONE 32T

    TBONE 32T New Member

    Joined:
    Aug 28, 2010
    Messages:
    3
    Loc:
    Central Illinois
    To me im thinking the air issue is from above the chimney passes through into a ventilated attic, and there was never a ceiling installed to seperate the attic air from the outside of the firebox, this issue is very common on new construction, a firestop would need to be installed and perhaps drywall or osb to seperate the attic air from the firebox. Also the walls surrounding the fireplace if the rear wall is an exterior should be not only insulated but drywalled, and yes certainly do not block off any air passages on the fireplace during operation.
  4. flusher17

    flusher17 Member

    Joined:
    Jun 3, 2010
    Messages:
    53
    Loc:
    ADKs, Northern NY
    I had the exact same problem and I am in the process of ripping the fireplace unit out. Then I am going to install a free standing woodstove on the hearth and close off the old hole in the house to look like a fireplace.

    I tried to block the drafts in the old unit by sealing the box it was in from the outside, but it never worked. I am sure that I lost more heat than I ever gained burning with it.
  5. Dakotas Dad

    Dakotas Dad Minister of Fire

    Joined:
    Mar 19, 2009
    Messages:
    1,352
    Loc:
    Central Kentucky
    Pictures.. we need pictures.
  6. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
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    49,037
    Loc:
    South Puget Sound, WA
    ancient thread arises out of the boneyard.
  7. flusher17

    flusher17 Member

    Joined:
    Jun 3, 2010
    Messages:
    53
    Loc:
    ADKs, Northern NY
    Look for a thread titled "Destroyed Hearth" for photos of what I have done so far. Today I am starting the rebuild. I'll try to get some photos of that process.
  8. mtj53

    mtj53 Member

    Joined:
    Feb 16, 2009
    Messages:
    62
    Loc:
    Northwest Illinois
    Jeffs,
    I also had the exact same problem you describe. Mine was so bad, I couldn't even take my insulation cover off to use the firepace because everything was so cold I couldn't get a draft no matter what I did. Much as I hated to do it, I ripped the nice brick & beautiful oak mantle off and started from scratch. What I found underneath simply amazed me. There was no insulation in the chase, the stack was not insulated, and no insulation at the top of the chase either. We ended up insulating the chase & putting in the RSF Opel, last year was the first year and even being a novice, we never had to turn the furnace on once. Even without the new RSF Opel going, it made a HUGE difference in the room the fireplace is in. Now I wish I'd have done it 20 years ago. I used to get frost an inch thick around the entire fireplace, not anymore!

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